Fast track to the overdoped regime of superconducting YBa2Cu3O7-{\delta} thin films via electrochemical oxidation

TL;DR

This paper introduces an electrochemical method to precisely control oxygen doping in YBa2Cu3O7-δ thin films, enabling exploration of the overdoped regime crucial for understanding and enhancing high-temperature superconductivity.

Contribution

It demonstrates for the first time the use of electrochemical oxidation to access and control the overdoped region in YBCO thin films, expanding experimental capabilities.

Findings

Achieved precise bulk oxygen control across the full doping range

Confirmed high doping states and critical current densities with multimodal characterization

Opened pathways for developing cleaner, overdoped cuprate superconductors

Abstract

High temperature superconductors, especially YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO), are considered a key enabling technology towards a clean energy future. Hole doping in YBCO is a prerequisite for the emergence of its unchallenged superconducting properties. Up to now, research was focused on the under- and optimally doped region, due to practical limitations in reaching the overdoped state, despite being highly interesting from fundamental and applied aspects as competing orders vanish and critical current densities are expected to peak. Here, we deploy for the first time an electrochemical method to access the mostly uncharted overdoped region. We demonstrate precise control over the bulk oxygen concentration in YBCO thin films across the full off-stoichiometry window (0$\le{\delta}\le$1) using electrochemical oxidation combined with in situ XRD and electrical measurements. Resulting high doping states and critical current densities are confirmed using a multi modal approach, including x-ray diffraction, electrical, Hall and magnetic characterization. Thus, this work opens a promising pathway based on electrochemical oxidation towards electronically clean, oxygen overdoped cuprate superconductors and therefore will assist to further push the critical current density to its intrinsic limit.